D.  The McStas terminology

This is a short explanation of phrases and terms which have a specific meaning within McStas. We have tried to keep the list as short as possible with the risk that the reader may occasionally miss an explanation. In this case, you are more than welcome to contact the McStas core team.

• Arm A generic McStas component which defines a frame of reference for other components.

• Component One unit (e.g. optical element) in a neutron spectrometer. These are considered as Types of elements to be instantiated in an Instrument description.

• Component instance A named Component (of a given Type) inserted in an Instrument description.

• Definition parameter An input parameter for a component. For example the radius of a sample component or the divergence of a collimator.

• Input parameter For a component, either a definition parameter or a setting parameter. These parameters are supplied by the user to define the characteristics of the particular instance of the component definition. For an instrument, a parameter that can be changed at simulation run-time.

• Instrument An assembly of McStas components defining a neutron spectrometer.

• Kernel The McStas meta-language definition and the associated compiler mcstas.

• McStas Monte Carlo Simulation of Triple Axis Spectrometers (the name of this package). Pronunciation ranges from mex-tas, to mac-stas and m-c-stas.

• Output parameter An output parameter for a component. For example the counts in a monitor. An output parameter may be accessed from the instrument in which the component is used using MC_GETPAR.

• Run-time C code, contained in the files mcstas-r.c and mcstas-r.h included in the McStas distribution, that declare functions and variables used by the generated simulations.

• Setting parameter Similar to a definition parameter, but with the restriction that the value of the parameter must be a number.